1. Field of the Invention
This invention relates to an X-ray CT (Computerized Tomography) scanner device, and more particularly to a device which has a detector array including a plurality of detector modules each of which is formed of a preset number of X-ray detectors and which is constructed to prevent occurrence of a number of fine linear noises which are so-called linear artifacts caused by a breakdown of the detector module and radiated from that point on a tomographic image which corresponds to the damaged detector module.
2. Description of the Related Art
Recently, Rotates/Stationary type X-ray CT scanner devices or X-ray CT scanner devices of so-called fourth-generation type, in which a detector array having a large number of detectors is arranged over an angle of 360.degree. around an object to completely surround the same and only an X-ray tube is rotated around the object, are frequently used. The detector array is constituted by a large number of detector modules each of which is formed of a preset number of X-ray detectors (one detector correspond to one channel) and which are arranged around the object in an annular configuration with no gap therebetween. In general, the number of detector modules constituting the detector array is more than several tens and each module has several tens of channels, and therefore the total number of channels may be several thousands.
Generally, in the X-ray CT scanner device, when one of the detectors becomes defective and X-ray projection data of a corresponding channel becomes invalid, data of the defective channel can be created by an interpolation method or the like using normal data of two adjacent channels. However, in a device such as a fourth-generation X-ray CT scanner device in which a plurality of detectors are used to constitute one detector module, if a detector module becomes defective, a plurality of successive channels are determined as defective channels, and it becomes impossible to derive data of all of the channels of one module by the interpolation method using the data of the adjacent channels. When one module becomes defective, a large number of fine linear artifacts which are radiated from that point on a tomographic image which corresponds to the defective detector module are caused on the tomographic image, and the tomographic image cannot be used for the diagnosis. For this reason, if at least one detector module becomes defective in the prior art, the entire device is treated as system-down and is not used until the module is replaced. That is, the device cannot be used for the diagnosis until the replacement or repair of the defective module is completed. If the system-down occurs in the night time, it tends to last long. However, since this type of device can be frequently used as a means for rapidly producing the result of the diagnosis in the emergency case, the long-term system-down may cause a serious problem.